Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers).
Gradient sensors are sensors that employ a voltage variation across one or more electrodes (usually a transmitter electrode) to assist in determining positional information. While gradient sensors are advantageous in a number of respects, there remains a need for gradient sensors capable of simultaneously sensing more than one input object present within a sensing region.